package com.bang.study.nio.socket;

import org.junit.Test;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;

/*
 * 一、使用 NIO 完成网络通信的三个核心：
 *
 * 1. 通道（Channel）：负责连接
 *
 * 	   java.nio.channels.Channel 接口：
 * 			|--SelectableChannel
 * 				|--SocketChannel
 * 				|--ServerSocketChannel
 * 				|--DatagramChannel
 *
 * 				|--Pipe.SinkChannel
 * 				|--Pipe.SourceChannel
 *
 * 2. 缓冲区（Buffer）：负责数据的存取
 *
 * 3. 选择器（Selector）：是 SelectableChannel 的多路复用器。用于监控 SelectableChannel 的 IO 状况
 *
 */
public class TestBlockingNIO {


    @Test
    public void client() throws IOException {
        //1. 获取通道
        SocketChannel socketChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 18888));

        FileChannel fileChannel = FileChannel.open(Paths.get("readme.md"), StandardOpenOption.READ);

        //2. 分配指定大小的缓冲区
        ByteBuffer buffer = ByteBuffer.allocate(1024);

        //3. 读取本地文件，并发送到服务端

        while (fileChannel.read(buffer) != -1) {
            buffer.flip();
            socketChannel.write(buffer);
            buffer.clear();
        }
        //4. 关闭通道
        fileChannel.close();
        socketChannel.close();

    }

    @Test
    public void server() throws IOException {
        //1. 获取通道
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        FileChannel fileChannel = FileChannel.open(Paths.get("3.md"), StandardOpenOption.READ, StandardOpenOption.WRITE, StandardOpenOption.CREATE);

        //2. 绑定连接
        serverSocketChannel.bind(new InetSocketAddress(18888));

        //3. 获取客户端连接的通道
        SocketChannel accept = serverSocketChannel.accept();

        //4. 分配指定大小的缓冲区
        ByteBuffer buffer = ByteBuffer.allocate(1024);

        //5. 接收客户端的数据，并保存到本地
        while (accept.read(buffer) != -1) {
            buffer.flip();
            fileChannel.write(buffer);
            System.out.println(new String(buffer.array()));
            buffer.clear();
        }

        //6. 关闭通道
        accept.close();
        fileChannel.close();
        serverSocketChannel.close();

    }
}
